Realization of a Λ system with metastable states of a capacitively-shunted fluxonium

  1. Nathan Earnest,
  2. Srivatsan Chakram,
  3. Yao Lu,
  4. Nicholas Irons,
  5. Ravi K. Naik,
  6. Nelson Leung,
  7. Jay Lawrence,
  8. Jens Koch,
  9. and David I. Schuster
We realize a Λ system in a superconducting circuit, with metastable states exhibiting lifetimes up to 7ms. We exponentially suppress the tunneling matrix elements involved in spontaneous